Physica Medica: European Journal of Medical Physics - Volume 32 - Supplement 1 - February 2016

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Non-Ionizing Radiations
F.454
COMMENTS ON THE SOUND PERCEPTION IN CONFINED ENVIRONMENT
AND IMPLICATIONS ON HEARING AIDS
E. Ruello G. Acri R. Bruno G. D’arrigo C. Sansotta G. Vermigli
a Università degli Studi di Messina, Messina, Italy; b Laureato in Tecniche
Audioprotesiche, Messina, Italy
Introduction: In confined environment sound vibrations perceived by the
ears are constituted by a complex set of primary waves from the sound
source and by reflected secondary ones. Another phenomenon is added due
the propagation of sound waves between reflective surfaces giving rise to
the ‘standing waves’.
In normoacousic people, ears can focus on primary source by binaural lis-
tening so it is just the phase difference and intensity linked to the position
of the receptors that integrates the most information.
The auditory system gives the sensation that the source is unique, as if the
primary wave overhangs and gates each reflected repetition.
The introduction of hearing aids generates distortions in time and phase
in binaural listening. This alters the natural sound message decoding and
produces distortions in the acoustic message.
Materials and Methods: Investigations carried out with advanced instru-
mentation include spectral analysis and statistics of primary and reflected
acoustic waves pointing out the qualitative and quantitative alterations that
occur in confined locations.
The tests were made by saturating with pure tones a standard room.
Electroacoustical diffuser connected to a generator of sinusoidal tones in
the range 100 Hz–6.3KHz was positioned in a room and intensity levels of
the most significant harmonic components were recorded simulating a bin-
aural listening.
Results: It can be observed experimentally that standing waves give a char-
acteristic acoustic timbre that will change for each sound and in any specific
point of the environment. These phenomena can be avoided and our au-
ditory system adapted for distortions in the perception of a sound message
naturally when listening is operated directly from our external apparatus
binaural, without the aid of artificial systems which reduce the large natural
capacity of hearing of adding sound waves.
Conclusion: The study outcomes can provide further guidance on the plan-
ning and adaptation of hearing aids in deaf patients.
F.455
NOISE EXPOSURE OF WORKERS AND PASSENGERS ON REGIONAL TRAINS
IN CALABRIA
G. Acri B. Testagross V. Faraone C. Sansotta E. Ruello L. Denar
G. Vermiglio a Department of BIOMORF, Messina, Italy
Introduction: In occupational environment noise is one of the major noxious
factors. Due to intensive industrialization and urbanization followed by traffic
increase, noise has become a ubiquitous stressful factor, both in living and
occupational environments. There are two major target areas for noise re-
search: (a) noise affects the person who is annoying, (b) noise affects the
person who works by impairing his performance. The aim of our study was
to measure noise levels on train, during workers commute, in order to eval-
uate a possible relationship between noise dose and worker health response.
Materials and Methods: To perform our measurements we used person-
al noise dosimeters to measure time integrated noise levels. The dosimeters
were worn by operators positioning the microphone close to their ear. The
measurements were conducted aboard trains, during commuting to and
from worker jobs, on the line Cosenza–Villa S. Giovanni (duration: 2,30
hours). At the end of each measurement the stored data were down-
loaded and analyzed using the dedicated software. Noise annoyance was
estimated using self-reported annoyance scale.
Results: All measurements performed had equivalent levels appreciably
above 80 dBA, where threshold limits, in Italian Legislation, is 80 dBA for
workers and 70 dBA for public. These values could be induced not only an-
noyance but also acute effects. Noise annoyance shown strong correlation
with noise levels. Dose–response relationship was found between the per-
centage of highly annoyed workers and Leq.
Conclusions: Noise exposure evaluated on Regional trains of the Cosenza–
Villa S. Giovanni line put in evidence that the limits recommended by Italian
legislation, both for workers and public, were exceeded. In addition,
exposure–effect relationships for train noise and noise annoyance have been
estimated. This relationship could be used as a national reference.
F.457
DEVELOPMENT OF A COMPUTATIONAL TOOL FOR HIFU ABLATION
THERAPY TO ASSURE SAFETY OF THE PATIENT
B. Caccia S. Pozzi C. Borrazz M. Carn E. Di Castro S. Valentini
a Istituto Superiore di Sanità, Roma, Italy; b Policlinico Umberto I, Università
La Sapienza, Roma, Italy
Introduction: High Intensity Focused Ultrasound (HIFU) is being investi-
gated for routine clinical practice with the aim of enabling thermal ablation
of tumors, also associated to others therapies, e.g. radiation therapy. HIFU
treatment is based on the power of a focused ultrasound beam to locally
heat biological tissues over a necrotic level with minimal impact on the
surrounding tissues. The clinical practice requires a standardization of quality
assurance protocols and the development of computational tools to eval-
uate the output of clinical HIFU devices and to ensure safe delivery of HIFU
treatment.
Materials and Methods: In this work we extended the HIFU Simulator,
an algorithm implemented by J.E. Soneson (Soneson JE. A User-Friendly
Software Package for HIFU Simulation. AIP Conf Proc 2009;1113:165,1709–
1719) for simulating HIFU beams and thermal dose distribution in biological-
equivalent tissues. To evaluate the behavior of the ultrasound beam in
presence of different tissues, a multilayer model has been implemented
to simulate different materials between the pressure source and the
target region.
Results: The extended HIFU Simulator has been tested on a multilayer math-
ematical phantom. All the computational aspects of the model, including
the numerical methods used to solve the equation of the ultrasound prop-
agation and the heat distribution in different equivalent tissues, have been
evaluated.
Conclusion: A wider acceptance of HIFU as a therapeutic modality re-
quires tools for the quality assurance protocols. Numerical simulation of
heat propagation in different biological tissues represents a useful tool for
computational dosimetry and to simulate the behavior of different bio-
logical tissues during the treatment.
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